1. Field of the Invention
The invention relates to subscriber stations for use in radio telecommunications networks and, more particularly, to a system for the logging of calls within such subscriber stations.
2. History of the Related Art
Cellular radio communications is, perhaps, the fastest growing field in the world-wide telecommunications industry. The convenience of subscriber mobility and the ability to place and receive telephone calls regardless of where the subscriber's telephone instrument is located has introduced a new era. The convenience of telecommunications without the restrictions of a physical telephone cable limiting the mobility of the telephone instrument is a great advantage. Mobile radio telecommunications may be implemented using different technologies including land mobile radio technologies, cellular radio, and personal communication systems (PCS). Hereinafter, the reference to cellular radio telecommunications systems will be intended to include each of these other telecommunication systems which employ portable subscriber stations. In such systems, the geographic range within which the subscriber station may move is determined strictly by the radio coverage area of one or more radio base stations with which the subscriber station can communicate.
The convenience of mobility of subscriber stations within the cellular radio network has facilitated new business opportunities in the field of the short term rental of portable cellular subscriber stations. Such businesses rent to a customer for the limited period of a day, a few days, a week or similar short term periods a complete portable subscriber station having cellular radio telecommunication service already established and an existing phone number and which is ready to use. Such rentals are often combined with the rental of automobiles so that mobile communications is available to a traveller using a rental car in a city away from his home.
In most cases, the rental period for which such cellular subscriber stations are rented are considerably shorter than the normal billing interval established by the operator of the cellular system. Thus, there arises a problem of knowing how to charge and what amount to charge to the renter of a cellular subscriber station since it's impossible for the rental company to know what calls to what locations and what charges have been incurred by the renter during the period of the rental contract. One way in which this is handled today is by requiring the renter to establish a credit card account with the rental company so that when the charges from the cellular system operator are received by the rental company, those charges can be debited directly against the credit card account and the detail record of the calls thereafter furnished to the credit card holder. This solution has a number of disadvantages in that the time lag between the use of the rented telephone instrument and the receipt of the charges from the cellular system operator can produce increased risks for the rental company in the form of termination of credit by the credit card company. In addition, it would be highly desirable to be able to furnish the renter of the telephone instrument a complete record of his charges at the time he returns the telephone instrument so that he can in turn process his own business expense statement and accounting records promptly after those charges are incurred.
While the accounting and billing system of the cellular radio operator maintains a complete record of all calls and charges therefor to every cellular telephone subscriber, those records must be processed in an orderly way and cannot be done on a daily or weekly basis. Thus, there exists a need for a means for monitoring and storing directly within a portable subscriber instrument, what calls have been made with the instrument, the parties called, the length of the calls and the resulting charges which have been incurred. The present invention provides such a means. The systems of the prior art do not provide telephone call charging information for a portable cellular subscriber station in a sufficiently real-time manner that the rental period of a cellular phone is virtually always shorter than the billing intervals for that cellular phone by the system operator.